Page 12 - AJWEP-22-5

Rajak, et al.

Table 2. Enzymes for inedible oils transesterification
Catalyst Feedstock Reaction operating conditions References
Solvent Molar Temperature Time Yield
ratio (°C) (h) (%)
Lipozyme Thermomyces Castor oil Methanol 3:1 45 24 60 78
lanuginosus immobilized
Burkholderia cepacia Jatropha curcas Ethanol 10:1 35 24 100 79
Candida parapsilosis lipase Jatropha curcas Methanol 2:1 30 8 80.50 80
Candida parapsilosis lipase Pistacia chinensis Methanol 5:1 37 60 90 81
Candida parapsilosis lipase Bungeseed oil Methanol 5:1 37 60 91 38
Candida parapsilosis lipase Calophyllum inophyllum Methanol 12:1 35 25 92 82

80.5% yield. In another study, Pistacia chinensis Bunge reduction in catalytic activity as a result of enzyme
seed oil was transesterified with methanol at a 5:1 molar inhibition. Many bacterial species, such as Pseudomonas
88
ratio, 37°C for 60 h, yielding 90% biodiesel. Similarly, fluorescens, Pseudomonas cepacia, Rhizomucor miehei,
C. inophyllum oil underwent transesterification with Rhizopus oryzae, Candida rugosa, T. lanuginosus, and
methanol at a 12:1 molar ratio, 35°C for 25 h, resulting in Candida antarctica, have been exploited as catalysts.
a 92% yield. These studies demonstrate the potential of Lipozyme T. lanuginosus immobilized, Lipozyme
using enzymes as biocatalysts for biodiesel production R. miehei immobilized, Novozym 435, and Ps-C are
from inedible oils, offering an environmentally some of the most researched immobilized lipases. 89-92
friendly alternative to traditional chemical catalysts. Throughout transesterification, catalysts are
The yields achieved vary depending on the enzyme influenced by several parameters, as shown in Figure 1.
used, feedstock, molar ratio, temperature, and reaction These factors are divided into fundamental parameters
time, indicating the need for optimization to maximize and sub-parameters in the figure. To provide a visual
efficiency. The high yields observed in some cases, depiction of how these variables impact enzyme activity
such as with B. cepacia lipase, suggest that enzymatic throughout the transesterification reaction, Figure 1
transesterification can be a viable method for producing illustrates the connections and interactions between
biodiesel from non-edible oils. them.
Since enzymes work well in a variety of processes, One of the many difficulties encountered in biodiesel
they are frequently regarded as the best substitutes production is the instability of free enzymes under
for chemical catalysts. Naturally occurring lipases different transesterification circumstances. In addition
83
are useful for producing biodiesel because they can to complicating enzyme recycling, the instability
effectively perform esterification and transesterification makes it challenging to separate the reaction mixture.
93
reactions. Enzymes aid in chemical processes without Scientists have focused on immobilizing enzymes
being consumed or changed. 84,85 Two types of enzymes onto solid carriers as a solution to these challenges.
often employed in the transesterification process for the By keeping the enzymes from becoming denatured,
production of biodiesel are extracellular and intracellular these carriers improve their chemical and thermal
lipases. Lipases that are intracellular remain within the stability. However, potential issues include decreased
94
86
cells or are affixed to the cell walls, whereas extracellular catalytic activity, enzyme dissociation, and structural
lipases are recovered from microbial broths and refined alterations due to interactions with the support matrix.
for use as catalysts. Compared to traditional catalysts, In addition, the price of the support materials may also
enzymes have a number of benefits, such as quicker be a constraint. 95
catalyst separation, lower energy consumption, greater Numerous lipase immobilization techniques have
glycerol purity, less soap generation during reactions, been investigated to enhance the generation of biodiesel.
simpler production procedures, and the capacity to By binding enzymes to inert materials, immobilization
reuse immobilized enzymes. 87 enables them to withstand variations in temperature,
Nonetheless, these enzymes possess several moisture content, and pH. Common methods include
disadvantages, including decreased reaction rates, cross-linking, trapping, encapsulation, covalent
increased expenses for lipase manufacture, and a bonding, and adsorption. These techniques attempt to
96

Volume 22 Issue 5 (2025) 6 doi: 10.36922/AJWEP025130095